NASA announced last week that Jupiter's Ganymede, the largest moon in the solar system, may have multiple oceans of liquid water under the surface. So we kind of have to ask: will we find life there?
We might, but finding it is going to be tricky. Even Europa, long considered a candidate for extraterrestrial life, isn't very high on the NASA or ESA priority list. And when we do prioritize Ganymede, the sectioned underground oceans could mean multiple missions that treat each layer of ocean as if they were a separate planet. The fact that Earth is teeming with surface life tells us very little about our own subterranean oceans, for example, and we live here.
And as we dig into all these extraterrestrial underground oceans, we need to be mindful that we're just exploring new environments and not accidentally destroying them. If a sheet of ice is the only thing separating a thriving ecosystem from total environmental collapse, drilling a hole through that sheet of ice in the name of science could put us in the position of exterminating the only alien life we've found. Until we can figure out non-invasive ways to explore multiple layers of subterranean ocean, staying away and leaving these questions unanswered is probably the right thing to do.